• Plasma exchange, together with oral immunosuppressive drugs and various doses of adrenal steroids, were used in the treatment of ten patients with pemphigus. Initially plasma exchange decreased the intercellular antibody (IC Ab) level in all patients and induced a clinical improvement in the conditions of eight of ten patients. This improvement was sustained for the six patients who received simultaneously 0.5 mg/kg/day or more of prednisone. Among the eight patients, four previously corticoresistant patients had perfect control of their disease. Conversely the other four patients, treated with low doses of prednisone. experienced a posttreatment rebound in IC Ab level and showed no or only transient clinical improvement. Plasma exchange may be useful in bringing corticoresistant pemphigus under control but it is not to be used without accompanying high doses of adrenal steroids.